Aortic dissection resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Serge Korjian M.D.; Chetan Lokhande, M.B.B.S [2]; Pratik Bahekar, MBBS [3]

Aortic dissection resident survival guide Microchapters
Overview
Classification
Causes
FIRE
Diagnosis
Treatment Medical Surgical
Do's
Dont's

Overview

Aortic dissection (AD) is a disruption of the medial layer of the aorta triggered by intramural bleeding. It is commonly due to an intimal tear that causes tracking of blood in a dissection plane within the media. Blood accumulation results in a separation of the aortic wall layers with ensuing formation of a true lumen and a false lumen with or without communication between the two. Aortic dissection is a medical emergency and can quickly lead to death if not managed urgently. Patients classically present with abrupt onset of severe, knife-like chest (most common), back, or abdominal pain. Other important features that increases the probability of aortic dissection include pulse deficits, systolic blood pressure differences between limbs, focal neurologic deficits, new aortic murmurs, shock, and a history of connective tissue disease and aortic valve disease. CT, MRI, or transesophageal echocardiography (TEE) may be used for the diagnosis AD, although CT is preferred because of it's speed, excellent sensitivity, and superiority in diagnosing arch vessel involvement. Serial imaging is recommended to monitor for progression of the dissection. After excluding possible aortic regurgitation, intravenous beta-blockers should be initiated in all patients to reduce the systolic blood pressure (SBP) to 100 to 120 mmHg and controlling the heart rate, to minimize the shear stress on the aortic wall. Treatment depends on the anatomic location of the dissection and complications. Uncomplicated type B dissections should be treated medically whereas type A dissections and complicated type B dissections should be treated surgically. Complications of AD include aortic regurgitation, myocardial ischaemia or infarction, pleural effusion, stroke, mesenteric ischemia, and acute kidney injury.

Classification

DeBakey and Stanford systems are the commonly used systems to classify aortic dissection.

Proximal Dissections

Originate in the ascending aorta and may propagate to involve the aortic arch, and possibly part of the descending aorta (include Debakey type I and II, and Stanford type A)

Distal Dissections

Originate in the descending aorta (distal to left subclavian artery) and propagate distally, rarely extends proximally (include Debakey type IIIa and IIIb, and Stanford type B)

Click here for the detailed classification schemes.

Causes

Life Threatening Causes

Aortic dissection is a life-threatening condition and must be treated as such irrespective of the underlying cause.

Common Causes

• Hypertension (underlying cause in 70%)
• Pre-existing aortic diseases or aortic valve disease
• Blunt chest trauma
• Complication of cardiac procedures
• Connective tissue disorders
• Vasculitis
• Intravenous drug use (cocaine and amphetamines)

Click here for the complete list of causes.

FIRE: Focused Initial Rapid Evaluation

A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.
Boxes in red signify that an urgent management is needed.

Abbreviations: AVR: Aortic valve replacement; BP Blood Pressure, CCU: Coronary care unit; CHF: Congestive cardiac failure; CXR: Chest X-ray; EKG: Electrocardiogram; MI: Myocardial infarction; OR: Operating room; TAVR: Transcatheter aortic valve replacement; TEE: Transesophageal echocardiogram; TTE: Transthoracic echocardiogram; HEENT: Head eye ear nose throat

Identify cardinal findings that increase the pretest probability of acute aortic dissection ❑ Chest pain or back pain or abdominal pain ❑ Sudden in onset ❑ Tearing or sharp in quality ❑ Increasing in intensity Associated with any of the following: ❑ Unexplained syncope ❑ Focal neurological deficits ❑ Unequal pulses or BPs in the limbs ❑ Perfusion deficits ❑ Refractory hypertension (decreased renal perfusion) ❑ Tensed abdomen ❑ Progressive metabolic acidosis ❑ Increasing liver enzymes

Does the patient have the following findings which require urgent management? ❑ Hypotension or shock ❑ Perfusion deficits

Yes

No

Attempt to stabilize patient ❑ Attend to the patient's ABCs (Airway, Breathing, Circulation) ❑ Consider intubation if the patient's airway is compromised, has a glasgow coma scale (GCS < 8) or profound haemodynamic instability ❑ Administer oxygen and maintain a saturation >90% ❑ Secure 2 large-bore intravenous lines (IVs) and initiate fluid resuscitation ❑ Titrate fluids to a mean arterial blood pressure of 70 mm Hg, overzealous fluid administration may lead to progression of the dissection ❑ Consider vasopressors only if patient remains hypotensive despite fluids ❑ Obtain 12 lead ECG and place the patient on a cardiac monitor ❑ Consider intra-arterial BP monitoring ❑ Place an indwelling urethral catheter and monitor urine output ❑ Frequently assess mental status and check for focal neurologic deficits ❑ Monitor development or progression of carotid, brachial, or femoral bruits ❑ Type and crossmatch patient for possible blood transfusion ❑ Obtain blood for CBC, electrolytes, BUN, creatinine, LFTS, and troponin I, and CK-MB Control blood pressure ❑ Beta blockers are first-line agents, as they circumvent the reflex tachycardia associated with blood pressure lowering ❑ Esmolol ❑ 500 micrograms/kg intravenous push initially, followed by 50 micrograms/kg/min for 4 min ❑ If necessary increase infusion up to 200 micrograms/kg/min OR ❑ Metoprolol ❑ 5 mg intravenously every 5-10 minutes ❑ If necessary increase up to a maximum dosage of 15 mg/total dose OR ❑ Labetalol ❑ 1-5 mg/min IV infusion OR ❑ Substitute with non-dihydropyridine calcium channel blockers if beta-blockers are contraindicated ❑ Diltiazem ❑ 0.25 mg/kg intravenous bolus initially then 5-10 mg/hr infusion ❑ If necessary increase dose to 15 mg/hr OR ❑ Verapamil ❑ 0.05 to 0.1 mg/kg IV bolus Control pain ❑ Morphine sulphate ❑ 2.5-5 mg every 3 to 4 hours, infused over 4-5 minutes

Continue with the diagnostic approach below

Urgent imaging required ❑ TEE (preferred in hemodynamically unstable) or CT looking for the following: ❑ Location and features of dissection ❑ Proximal vs. Distal ❑ Involvement of aortic branches ❑ Associated complications ❑ Pericardial effusion ❑ Regional wall motion abnormality ❑ Severe aortic regurgitation (AR)

Can aortic dissection be confirmed?

Yes

No

Proceed to Management Algorithm

Obtain a secondary imaging study, if there is high clinical suspicion

Complete Diagnostic Approach

A complete diagnostic approach should be carried out after a focused initial rapid evaluation is conducted and following initiation of any urgent intervention.

Characterize the symptoms: ❑ Chest pain ❑ Tearing, ripping, sharp. stabbing, or knife-like ❑ Sudden onset and increasing in intensity ❑ Worsened by deep breathing or cough and relieved by sitting upright (suggestive of hemorrhage into the pericardial sac). ❑ Neck, throat, and jaw pain ❑ Abdominal pain or back pain (think of associated mesenteric ischemia) ❑ Syncope in 50% of cases (suggestive of hemorrhage into the pericardial sac causing pericardial tamponade) ❑ Palpitation ❑ Rapid, weak pulse ❑ Dyspnea ❑ Rapid breathing ❑ Orthopnea ❑ Hemoptysis (suggestive of compression of and erosion into the bronchus) ❑ Stridor (suggestive of compression of the airway) ❑ Flank pain ❑ Oliguria/ anuria (suggestive of involvement of the renal arteries causing pre-renal kidney injury). ❑ Nausea and vomiting ❑ Dysphasia(suggestive of pressure on the esophagus) ❑ Hematemesis ❑ Gastrointestinal bleeding ❑ Altered mental status ❑ Symptoms suggestive of stroke e.g. paraplegia, numbness and tingling (suggestive of involvement of cerebral or spinal arteries) ❑ Horner's syndrome (suggestive of compression of the superior cervical ganglia) ❑ Drooping of eyelids (ptosis) ❑ Decreased or no sweating (anhidrosis) ❑ Miosis ❑ Hoarseness of voice (suggestive of compression of the recurrent laryngeal nerve) ❑ Claudication (suggestive of iliac artery occlusion) ❑ Painless dissection (15 – 55 %)(unexplained syncope, stroke or congestive heart failure (CHF))

Obtain a detailed history: ❑ Past medical history ❑ Hypertension (most important risk factor present in >70% of patients) ❑ Pheochromocytoma ❑ Family history ❑ Connective tissue disorder ❑ Marfan syndrome ❑ Ehlers-Danlos syndrome ❑ Loeys-Dietz syndrome ❑ Polycystic kidney disease ❑ Anatomic defects ❑ Biscuspid aortic valve ❑ Aortic valve disease ❑ Aortic root disorders ❑ Aortic aneurysm ❑ Coarctation of aorta ❑ Iatrogenic ❑ Recent aortic manipulation ❑ Chronic steroid usage ❑ Immunosuppressive therapy ❑ Social history ❑ Cocaine abuse ❑ Heavy weight lifting ❑ Trauma ❑ Other genetic disorders ❑ Turners syndrome (usually due to bicuspid aortic valve) ❑ Familial thoracic aneurysm and dissection syndrome ❑ Inflammatory vasculitis ❑ Takayasu arteritis ❑ Giant cell arteritis ❑ Behcet's arteritis ❑ Pregnancy ❑ Aortitis

Examine the patient: ❑ Obtain vitals: ❑ Pulse ❑ Tachycardia (suggestive of pain, aortic insufficiency, pericardial tamponade, and aortic rupture if associated with severe hypotension) ❑ Wide pulse pressure (suggestive of acute aortic insufficiency) ❑ Pulsus paradoxus (suggestive of pericardial tamponade) ❑ Pulse deficit involving carotid, femoral or subclavian artery ❑ Absent femoral pulse ❑ Blood pressure ❑ Difference in the blood pressure in both extremities ❑ Hypertension (due to pain and catecholamine surge) ❑ Hypotension (grave prognostic indicator, suggestive of pericardial tamponade, severe aortic insufficiency, or aortic rupture) ❑ Signs of shock (hypoperfusion) ❑ Hypotension (SBP < 90 mm of Hg or drop in mean arterial pressure >30 mm of Hg) ❑ Altered mental status ❑ Cold and clammy extremities ❑ Oliguria (urine output <0.5mL/kg/hr) ❑ Perform a HEENT examination looking for: ❑ Increased JVP (suggestive of heart failure) ❑ Horner's syndrome ❑ Hoarseness due to compression of the left recurrent laryngeal nerve ❑ Swelling of the neck and face (suggestive of superior vena cava syndrome) ❑ Perform a cardiovascular examination looking for: ❑ Faint early diastolic murmur (suggestive of acute aortic regurgitation, vs. loud decrescendo diastolic murmur of chronic AR) ❑ Pericardial friction rub (suggestive of pericarditis) ❑ Clicks (suggestive of pseudoprolapse/true prolapse of mitral and/or tricuspid valve) ❑ Beck's triad (suggestive of cardiac tamponade) ❑ Hypotension (suggestive of decreased stroke volume) ❑ Jugular venous distension (suggestive of venous hypertension due to decrease cardiac output) ❑ Muffled heart sounds (suggestive of fluid inside the pericardium) ❑ Perform a respiratory examination looking for: ❑ Kussmaul's sign (Paradoxical increase in jugular venous pressure with inspiration - Suggestive of tamponade) ❑ Decreased movement of the chest ❑ Stony dullness to percussion (suggestive of hemothorax and / or pleural effusion ❑ Diminished breath sounds ❑ Crackles / crepitations / rales (suggestive of pulmonary edema due to acute aortic insufficiency) ❑ Stridor and wheezing (suggestive of compression of the airway) ❑ Decreased tactile fremitus (suggestive of pleural effusion) ❑ Perform an abdominal examination looking for: ❑ Ascites ❑ Perform a full neurological examination looking for: ❑ Altered mental status ❑ Extremity tingling and numbness (suggestive of nerve compression) ❑ Focal neurological deficits (signs suggestive of stroke) ❑ Examine the extremities for: ❑ Peripheral edema ❑ Claudication

Consider alternate diagnosis: ❑ Aortic regurgitation ❑ Aortic stenosis ❑ Aortic aneurysm ❑ Atherosclerotic or cholesterol embolism ❑ Cardiac tamponade ❑ Cardiogenic shock/hypovolemic shock/hemorrhagic shock ❑ Esophageal perforation or rupture ❑ Hypertensive emergencies ❑ Musculoskeletal pain ❑ Mediastinal tumors ❑ Myocardial infarction ❑ Myocarditis ❑ Pancreatitis ❑ Peptic ulcer disease or perforating ulcer ❑ Pleural effusion ❑ Pulmonary embolism

Focused bedside pre-test risk assessment ❑ High risk conditions ❑ Marfan syndrome ❑ Connective tissue disease ❑ Family history of aortic disease ❑ Known aortic valve disease ❑ Recent aortic manipulation ❑ Known thoracic aortic aneurysm ❑ Aortic disorder ❑ High risk pain features ❑ Chest, back, or abdominal pain ❑ Abrupt onset ❑ Severe intensity ❑ Ripping, tearing, sharp, or stabbing ❑ High risk exam features ❑ Perfusion deficits ❑ Pulse deficit ❑ Systolic blood pressure differential ❑ Focal neurological deficit ❑ Murmur of aortic insufficiency ❑ Hypotension or shock

Low pre-test probability (No features present) High threshold for aortic imaging

Intermediate pre-test probability (1 feature present) Intermediate threshold for aortic imaging

High pre-test probability (2 or more features present) Immediate surgical evaluation and expedited aortic imaging

❑ Can an alternate diagnosis be identified?

❑ Order an EKG ❑ Does EKG show ST elevation ?

Yes

No

No

Yes

❑ Consider immediate surgical consultation and do aortic imaging as soon as possible

Treat accordingly

❑ Is there evidence of: ❑ Unexplained hypotension? ❑ Widened mediastinum on CXR?

❑ Can an alternate diagnosis be identified?

❑ Treat like a primary acute coronary syndrome (ACS) ❑ If perfusion deficits are present then consider immediate coronary reperfusion therapy ❑ Identifiable culprit lesion on coronary angiography?

No

Yes

No

Yes Treat accordingly

No

❑ Check risk factors for Thoracic aortic disease (TAD) ❑ Advanced age ❑ Risk factor for aortic diseases ❑ Syncope ❑ Do a detailed aortic imaging for thoracic aortic disease

Detailed and accelerated aortic imaging

❑ Aortic Imaging ❑ Transesophageal echocardiography (TEE) (preferred in unstable patients) ❑ Computed tomography(chest to pelvis; better visualization of aortic branch involvement) ❑ Magnetic resonance imaging(chest to pelvis)

❑ Can aortic dissection be confirmed by imaging study

Yes

No

❑ Start appropriate therapy

❑ Obtain a secondary imaging study if there is high clinical suspicion, even if the initial aortic imaging studies are negative

Treatment

Medical Management

Shown below is an algorithm summarizing the medical management of aortic dissection according to the 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for Diagnosis and Management of patients with Thoracic Aortic Disease.

Confirmed aortic dissection

❑ Consider urgent surgical consultation ❑ Consider transfer to other medical facility if resources not available for adequate management

❑ Is patient hemodynamically stable ?

Yes

No

Control rate and pressure (choose ONE of the following agents) ❑ Beta blockers Betablockers are contraindicated in bradycardia, heart block, decompensated heart failure, hypotension, asthma, severe chronic obstructive pulmonary disease ❑ Esmolol ❑ 500 micrograms/kg intravenous initially, followed by 50 micrograms/kg/min for 4 min ❑ If necessary increase infusion up to 200 micrograms/kg/min OR ❑ Metoprolol ❑ 5 mg intravenously every 5-10 minutes ❑ If necessary increase up to a maximum dosage of 15 mg/total dose OR ❑ Labetalol ❑ 1-5 mg/min IV infusion OR Substitute with non-dihydropyridine calcium channel blockers if betablockers are contraindicated ❑ Calcium Channel blockers Calcium channel blockers are contraindicated in hypotension, second- or third-degree atrioventricular block, sick sinus syndrome, left ventricular dysfunction, pulmonary congestion ❑ Diltiazem ❑ 0.25 mg/kg intravenous bolus initially then 5-10 mg/hr infusion ❑ If necessary increase dose to 15 mg/hr OR ❑ Verapamil ❑ 0.05 to 0.1 mg/kg IV bolus Titrate therapy: ❑ Goal heart rate of 60 beats per minute ❑ Goal systolic BP of 90-120 mm Hg Control pain ❑ Morphine sulphate ❑ 2.5-5 mg every 3 to 4 hours, infused over 4-5 minutes

❑ Type A dissection ❑ Surgical emergency, expedited transfer to operating room ❑ Intravenous fluid replacement ❑ Maintain euvolemic status ❑ Titrate to mean arterial pressure of 70 mm Hg ❑ Consider vasopressors if still hypotensive

❑ Type B dissection ❑ Intravenous fluid replacement ❑ Maintain euvolemic status ❑ Titrate to mean arterial pressure of 70 mm Hg ❑ Consider vasopressors if still hypotensive ❑ Rule out a possible complication causing hypotension: ❑ Aortic rupture ❑ Severe aortic insufficiency ❑ Pericardial tamponade ❑ Urgent surgical consultation

Systolic blood pressure still >120 mm Hg?

No

Yes

Can hypotension be corrected by surgical intervention?

Yes

No

Add IV vasodilator with SBP goal <120 mmHg ❑ Nitroprusside ❑ 0.3 to 0.5 micrograms/kg/min IV initially then increase by 0.5 micrograms/kg/min ❑ If necessary increase dose to a maximum of 15 mg/hr

Proximal dissection (involving ascending aorta)?

Yes

Proceed to Surgical Management

❑ Continue medical management ❑ Maintain SBP<120 mm Hg

No

❑ Continue medical management ❑ Maintain SBP<120 mm Hg

❑ Complications that require operative or interventional management? ❑ Limb or mesenteric ischemia ❑ Progression of dissection ❑ Aneurysm expansion ❑ Uncontrolled hypertension

Refer for surgical management

Surgical Management

Surgical management of aortic dissection according to the Guidelines for Diagnosis and Management of patients with Thoracic Aortic Disease.

Is the patient hemodynamically stable?

Yes

No

No

❑ Age > 40?

Yes

No

❑ Assess need for pre-operative coronary angiography ❑ Known CAD? ❑ Significant risk factors for CAD?

Yes

No

❑ Perform angiography Significant CAD detected on angiography?

Yes

❑ Plan for CABG at the time of aortic dissection repair

❑ Perform urgent operative management

❑ Evidence of any of the following? ❑ Aortic regurgitation ❑ Dissection of aortic sinuses

No

Yes

❑ Perform graft replacement of ascending aorta ± aortic arch

❑ Perform graft replacement of ascending aorta ± aortic arch ❑ Consider repair/replacement of aortic valve

Do's

History and Examination

• For pre-test risk determination include information about:
  • Medical history
  • Family history and ask specifically for family history of aortic dissection or thoracic aneurysm
  • Pain history
• Do a detailed physical examination to identify findings for certain high risk conditions like:(class I, level of evidence B)
  • Marfan's syndrome
  • Loeys-Dietz syndrome
  • Ehlers-Danlos syndrome
  • Turner's syndrome
  • Connective tissue disorder
• Check for genetic mutations predisposing to dissection:(class I, level of evidence B)
  • Fibrillin 1 (FBN1)
  • Transforming growth factor, beta receptor I (TGFBR1)
  • Transforming growth factor, beta receptor II(TGFBR2)
  • Alpha-actin-2(ACTA2)
  • Myosin-11 (MYHH11)
• Ask about recent aortic or surgical or catheter manipulation.(class I, level of evidence C)
• Ask in detail about the pain. Include the following: (class I, level of evidence B)
  • Onset of pain whether abrupt or instantaneous
  • Severity of pain
  • Quality of pain whether ripping, tearing, stabbing or sharp.
• Check for the following features on examination:(class I, level of evidence B)
  • Pulse deficits
  • Blood pressure (systolic) difference of above 20 mm of Hg in limbs
  • New onset aortic regurgitation features
  • Focal neurological deficits
• Patients less than 40 years of age and presenting with sudden onset chest, abdominal or back pain should be evaluated for high risk conditions.
• Patients presenting with features of syncope along with features of dissection should have a detailed neurological examination and cardiovascular examination to rule out pericardial tamponade and other neurological deficits.(class I, level of evidence C)

Screening Tests

• Do an emergent CT or a transesophageal echocardiography (TEE). If the patient is hemodynamically unstable, then a transesophageal echo can be performed in the operating room after the patient has been induced and is being prepared for surgery.
• Do a magnetic resonance imaging contrast aortography (MRI) only if:
  • A patient who has chronic chest pain who is hemodynamically stable
  • A chronic dissection
• Do an EKG when patients presents with symptoms of dissection.(class I, level of evidence B)
• Treat the patient as an acute cardiac event, if ST elevation is present in EKG then, unless the patient has high risk factors for acute dissection.
• Order an X-ray for all patients with intermediate to low risk to rule out an alternate diagnosis.(class I, level of evidence C)
• Evaluate high risk patients by transesophageal echocardiogram, computed tomography or magnetic resonance imaging to rule out dissection.(class I, level of evidence B)
• Obtain a secondary imaging study, if the initial aortic imaging studies are non conclusive, and there is a high clinical suspicion.(class III, level of evidence C)

• Do a plasma smooth muscle myosin heavy chain protein, D-dimer and high sensitive C-reactive protein to rule out alternate diagnosis.

Initial Management

• Medical management should be aimed at decreasing aortic wall stress.(class I, level of evidence C)
• Titrate beta blocker to maintain heart rate of 60 beats/ minute.(class I, level of evidence C)
• Use nondihyropyridine calcium channel blockers to control rate, if beta blockers are contraindicated.(class I, level of evidence C)
• Use angiotensin converting enzyme (ACE) inhibitors or vasodilators to maintain end organ perfusion, if BP remains above 120 mm of Hg, after medical treatment.(class I, level of evidence C).

Definitive Management

• Do a pericardiocentesis for pericardial bleeding and dissection related hemopericardium.
• Order a surgical consultation for all patients once diagnosed with aortic dissection. This applies to patients presenting with dissection at any location. (class I, level of evidence C)
• Perform an emergent repair in acute dissection of ascending aorta to prevent complications like rupture.(class I, level of evidence C)
• Consider surgical repair for all type A dissections as they involve the aortic valve. type A|Ascending aortic dissections (Type A Stanford)]] often involve the aortic valve, which having lost its suspensory support, telescopes down into the aortic root, resulting in aortic incompetence. This needs re-suspending to re-seat the valve and repair / prevent coronary artery injury. The area of dissection is removed and replaced with a dacron graft to prevent further dissection from occurring.
• Suspect malperfusion in type B aortic dissection, if following sings are present, Refractory hypertension (decreased renal perfusion), tensed abdomen, progressive metabolic acidosis, increasing liver enzymes (impaired perfusion of truncus celiacus, mesenteric arteries).
• Consider medical management for type B dissections, unless there is leaking, rupture or compromise to other organs, e.g. kidneys and life threatening conditions like perfusion deficit, dissection enlargement, aneurysm enlargement or blood pressure refractory to treatment.(class I, level of evidence C)
• Perform an MRI before discharge and repeat at 6 mo and 1 yr, then every 1 to 2 yr.

Dont's

• Don't delay aortic imaging even if chest x-ray is negative (class III, level of evidence C).
• Don't use beta blocker among patients with severe acute aortic regurgitation as they inhibit the compensatory tachycardia needed to maintain cardiac output.
• Don't use nitroprusside without a β-blocker or non-dihydropyridine calcium channel blocker in order to prevent reflex sympathetic activation which can increase aortic shear stress and potentially worsen the dissection.
• Hemorrhagic stroke is a relative contraindication to urgent surgical intervention done for type A tears, as intraoperative heparinization and restoration of cerebral blood flow can worsen ongoing stroke outcomes.

References